Info on value of Chris Evert signed racquet

Can someone please point me in the right direction to get the estimated value of the following and the best venues to offer it up for sale: The racquet (w/cover) that was in Chris Evert's hands when she won the 1977 US Open. The racquet was signed by Chris right after the match and Chris, as was her motto back then well before Nike, had written on both interior sides of the racquet cover "Do It!"